(a) Field of the Invention
The invention relates to improvements to an instrument for attacking calculi in a liquid medium surrounding the calculi which improvement comprises means for detecting whether the lithotrite of the instrument is abutting tissue of the patient. More specifically, the invention relates to such an instrument wherein the means for detecting comprises means for sensing the conductivity of the liquid medium.
(b) Description of Prior Art
Instruments of the above-described type, for example, instruments for disintegrating stones in a human patient, are known in the art as illustrated in, for example, U.S. Pat. No. 3,902,499, Shene, issued Sept. 2, 1975. The known instruments suffer the disadvantage of not having any indication when the lithotrite may be touching the tissue of a patient. As will be apparent, if the lithotrite is in such a position when discharged, then the patient can be hurt.